Dynamic footwear sole construction

ABSTRACT

A dynamic footwear midsole has an upper layer and a lower layer that are connected by a group of heel slats and a group of forepart slats, each slat being connected at hinge regions to the upper and lower layers. The slats in each group are arranged in generally paralleling planes with the heel slats and forepart slats being arranged to cause one group to collapse as the other group expands. An arch segment is provided at the midportion of the upper layer is constructed and supported by an arch support structure that enables the upper layer and arch support structure to rock, as a unit, about a pivot region at the lower end of the support structure.

RELATED APPLICATION

This application is a continuing application of prior pending U.S.application Ser. No. 17/220,400, filed Apr. 1, 2021 entitled FOOTWEARSOLE CONSTRUCTION.

FIELD

The present invention relates to sole structures for footwear and,particularly to footwear having an improved midsole structure.

BACKGROUND

Many types of footwear typically are formed on a last, a foot-shapedform. In a common construction an insole is temporarily attached to thebottom of the last and an upper is draped and stretched over and aboutthe last and the margins of the upper are attached to the peripheralmargins of the insole. An outsole then is attached to the shoe bottom.In many types of footwear, for example only, in athletic shoes, amidsole may be provided between the insole and outsole. The midsole mayfunction to provide stability and cushioning for the user's foot, toenhance comfort, reduce risk of injury or to serve other functions.Midsoles commonly are formed from resilient polymeric materials and mayhave varying degrees of compressibility, resilience and othercharacteristics depending on the combinations of materials used, midsoleshape and geometry.

It is among the general object of the present invention to provide animproved midsole construction and improved footwear embodying animproved midsole structure.

SUMMARY

A midsole is provided to have distinct, spaced upper and lower layers,each layer having a peripheral contour approximating a human footprint.The upper layer has an arch support that includes an arched segmentformed in its mid-region. The upper and lower layers are connected by aplurality of slats that extend transversely of the midsole. The slatsare arranged in two groups, including a forepart group located betweenthe arched segment and the toe region and a heelward group locatedbetween the arched segment and heel end of the midsole. The slats in theforepart group are inclined in an upward and toeward attitude and are ingenerally paralleling planes and the slats in the heelward group areinclined in an upward and heelward attitude, and also are in a generallyparalleling planes. The junctions of the slats with the upper and lowerlayers are formed to define hinge regions that enable the upper layer tomove relative to the lower layer as the user walks or runs. Each pair ofadjacent slats and the segments of the upper and lower layers connectingthose adjacent slats form a prism-like void with a cross-section thatfunction as a four-bar linkage. As a user's weight shifts between theheel and forepart portions the shapes of the prism-like voidsalternately expand and contract with the heel voids expanding as theforepart voids contract and vice versa. The region beneath the archedsegment is braced and reinforced to define, with the arched segment, arelatively stiff arch support structure that is resistant to heightwisecompression and is attached to the lower layer at a pivot region in amanner that enables the upper layer and arch support structure to pivotas a unit with the pivot region acting as a fulcrum to support the footas weight is transferred from heel to toe in a walking or running gait.

THE DRAWINGS

The objects and advantages of the invention will be apparent more fullyfrom the following description, with reference to the accompanyingdrawings in which:

FIG. 1 is a somewhat diagrammatic side view of a shoe having a midsolein accordance with an embodiment of the invention;

FIG. 2 is a plan view of the midsole as seen from 2-2 of FIG. 3 ;

FIG. 3 is a side view of the midsole;

FIGS. 4A and 4B are views of heel slats as seen along the lines 4A-4Aand 4B-4B of FIG. 2 ;

FIGS. 4C and 4D are views of forepart slats as seen along the lines4C-4C and 4D-4D of FIG. 2 ;

FIG. 5 is a somewhat diagrammatic, longitudinal section of the midsolewhen a runner's weight is on the heel, as shown in FIG. 5A;

FIG. 5A illustrates a runner with weight on the heel of the midsole;

FIG. 6 is a somewhat diagrammatic, longitudinal section of the midsolewhen a runner's weight is on the arch as shown in FIG. 6A;

FIG. 6A illustrates a runner with weight on the arch of the midsole;

FIG. 7 is a somewhat diagrammatic, longitudinal section of the midsolewhen a runner's weight is on the forepart, as shown in FIG. 7A; and

FIG. 7A illustrates a runner with weight on the forepart of the midsole;

FIGS. 8A and 8B are illustrations similar to FIGS. 4A and 4B of heelslats in a modified embodiment; and

FIGS. 8C and 8D are illustrations similar to FIGS. 4A and 4B of forepartof the invention. slats in a modified embodiment; and

FIG. 9 is an diagrammatic illustration of a user's foot with the user'sweight on the forepart of the midsole in the region of a modifiedforepart slat.

ILLUSTRATIVE EMBODIMENTS

As shown in FIG. 1 , an illustrative article of footwear, such as anathletic shoe, has an upper 10, an insole (not shown), a midsole 12 andan outsole 14. The midsole 12, also shown in FIGS. 2-5 , has upper layer16 and a distinct, spaced lower layer 18, both of which have aperipheral edge 20 in a general outline of a human footprint.

The midsole may be formed from any of a variety of commerciallyavailable polymers, as by injection molding or by using additivemanufacturing techniques (e.g., 3-D printing) and may be considered tohave a heel portion 22, a forepart portion 24 and a midportion 26between the heel and forepart portions 22, 24. The distinct upper andlower layers 16, 18 are connected together by a plurality of inclinedslats, including a group of forepart slats 28 and a group of heel slats30. The upper layer 16 is provided, in its midportion 26, with an archedsegment 32. As described in more detail below, the arrangements of heelslats and forepart slats allow the heel and forepart regions 22, 24 ofthe midsole to be resiliently compressed, alternately, while alsopermitting some relative longitudinal movement of the layers in responseto the shifting weight of the user when walking or running. In theembodiment shown in FIGS. 2 and 3 the slats 28, 30 may extendtransversely the full width of the midsole from the inner (medial) sideM to the outer (lateral) side L or may be modified as described below.As shown in FIG. 2 , the slats 28, 30 may be oriented at an angle A tothe midsole centerline 31 (extending between the heel and toeextremities of the midsole), preferably between about ten to abouttwenty degrees with the medial ends of the slats being disposed toewardof their lateral ends as I have found this to provide a more comfortableconfiguration. The principles of the invention, however, are not limitedto any specific angle, and in some cases the slats could extend closerto perpendicular to the centerline.

The slats within each group are disposed in generally paralleling planesand are attached to and extend between the upper and lower layers 16, 18at upper and lower hinge regions 34, 36, respectively. The hinge regionsand materials from which the midsole is formed should provide for acumulative, desired degree of resilience to provide cushioning as weightis applied as well as contributing to forward propulsion as the weightis transferred from heel to toe. It will be appreciated that thearrangement of any pair of adjacent slats and the segments (16 a, 16 b,. . . 16 n and 18 a, 18 b, . . . 18 n) of the upper and lower layersthat connect to that slat pair define and function as a four-bar linkagethat encloses a prism-shaped cell or void 38, the shape of which willchange as the heel and forepart portions respond to the shifting ofweight between the heel and forepart. The heelward and forepartprism-shaped cells 38 thus oscillate alternatively between expanded andcontracted configurations as the user's gait progresses. The differentorientations of the heelward and forepart slats cause the heelward cellsto collapse as the forepart cells expand and vice versa as seen in FIGS.5-7 .

Although the slats in each group are generally parallel to each other,the slats 30 of the heel group are not parallel to the slats 28 of theforepart group. Thus, as shown, the forepart slats 28 are inclined in anupward and toeward orientation; the heel slats 30 are inclined in anupward and heelward orientation. This orientation of the slats 28, 30,coupled with the compressive resistance and stiffness of the pivotablearch support structure of the midsole, provides a dynamic action inwhich an arch support structure 31, described below, and the upper layer16 can rotate together as a unit about a pivot region 35, whichfunctions as a fulcrum, as the user's weight shifts progressively fromheel to toe. Thus, as shown in FIGS. 5 and 5A, as a runner's heelengages the ground, the heel region of the midsole is compressed againstthe resilience of the heel region, causing the heel slats 30 to rotatewithin the midsole (counterclockwise as seen in FIG. 5 ). That, alsocauses the forepart portion 24 of the relatively stiff upper layer 16 topivot with the arch support structure relative to the lower layer andabout the pivot region, causing the forepart of the upper layer to moveaway from the lower layer 18 with the forepart slats 28 rotating (alsocounterclockwise) as the spacing between the forepart portions of theupper and lower layers increases. As the runner's weight unloads fromthe heel portion 22 and shifts to the midportion 26 (FIGS. 6 and 6A) andthen to the forepart portion 28 (FIGS. 7 and 7A), the upper layer andthe arch support structure pivots and the heel slats 30 and forepartslats 28 rotate within the midsole (clockwise) with the heelward cellsexpanding while the forepart cells contract.

The arched segment is contoured to support the arch region of the user'sfoot and, preferably, may be formed integrally as a unit with the upperlayer. The upper layer should be sufficiently stiff so that the slatsand their connecting segments of the upper and lower layers function asa four-bar linkages as described above, without significant distortionof the slats and connective segments (16 a, 16 b, . . . 16 n and 18 a,18 b, . . . 18 n) of the layers. The stiffness can be achieved byvarious combinations of material selection, dimensional adjustments, andembedded stiffeners, as will be familiar to those skilled in the art.The arched segment 32 and the arch support structure 31 should be theleast compressible portion of the midsole to facilitate its function asa fulcrum. To that end the arched segment may extend from the junctionregion of the most toeward slat 30 h of the heel group to the mostheelward forepart slat 28 f, both of which may be thicker or otherwisestrengthened and have more robust hinge regions to provide support forthe arched segment so as to serve as the arch support structure 31. Asshown in FIGS. 1 and 3 , the lower ends of the slats 28 f and 30 h thatsupport the arched segment are attached to the lower layer 18 in closeproximity to each other so that the arched segment 32 and more robustslats 28 f, 30 h define an approximately triangular configuration with alower apex formed by the region of juncture of the slats 28 f, 30 h andlower layer 31. The pivot region 35 functions as a fulcrum about whichthe upper layer 16 and arch support structure 31 together can pivot.Additional supporting braces may be included as supplemental supportbelow the arched segment as, for example, by one or more heightwise andlongitudinally extending support braces 33 extending between theunderside of the arched segment and the lower layer, the forward andrearward ends of the brace(s) 33 being attached to the support slats 30h and 28 f.

FIGS. 8, 8A, 8B, 8C and 8D illustrate modified embodiments of slats inwhich the one or both of the end regions of the slats may be modified byeliminating some end portions of some of the slats. In thismodifications, selected ends of selected slats may have cut-awayportions CA that have the effect of varying the degree of medial-lateralsupport provided by the midsole. For example, FIG. 8D illustrates anexample of a slat configuration with a greater cut-away on the medialend M of the slat than on the lateral end L so that the user's foot willtend to cant as shown in FIG. 9 . It will be appreciated that theconfigurations of the slats, as well as other parts of the midsole maybe modified to provide a midsole having support characteristics tailoredand customized to a particular user, for example, to provide enhancedperformance, greater comfort, an appropriate corrective function orother characteristic. Commercially available gait analysis systems maybe employed to analyze a user's gait so as to inform making of suchcustomized midsoles.

Dynamic midsoles in accordance with the invention are not limited to usein athletic footwear but may be used with other types of footwear suchas conventional shoes, sandals, hiking and other boots, flip-flops,among others. It should be understood that the foregoing description ofthe invention is intended merely to be illustrative thereof and thatother embodiments and modifications may be apparent to those skilled inthe art without departing from the principles of the invention.

1. A footwear midsole comprising: an upper layer; a lower layer spacedfrom the upper layer, the layers being distinct from each other; each ofthe upper layer and lower layer having a heel portion, a midportion anda forepart portion; the upper layer having an arched segment at themidportion; a relatively stiff arch support structure at the midportionof the midsole, the arch support structure supporting the arched segmentand extending between and connected to the upper and lower layers and; aplurality of generally planar heel slats extending transversely betweenand hingedly connected to the heel portions of the upper and lowerlayers; a plurality of generally planar forepart slats extendingtransversely between and hingedly connected to the forepart portions ofthe upper and lower layers; the arch support structure being ofsufficient strength to present greater resistance to heightwisecompression than the heel and forepart portions of the midsole, the archsupport structure having a lower portion attached to the lower layer todefine a pivot region about which the arch support structure may rock,as a unit, together with the upper layer, toeward and heelward about thepivot region as a stride progresses.
 2. The midsole as defined in claim1 further comprising: the heel slats being inclined in an upward andheelward direction; and the forepart slats being inclined in an upwardand toeward direction.
 3. The midsole as defined in claim 1 furthercomprising: the upper and lower layers and the slats being formed as aunitary, one-piece structure.
 4. The midsole as defined in claim 2further comprising: the upper and lower layers and the slats beingformed as a unitary, one-piece structure.
 5. The midsole as defined inclaim 2 further comprising: the arched segment extending from the mosttoeward of the heel slats to the most heelward of the heel slats.
 6. Themidsole as defined in claim 5 further comprising: the most toeward ofthe heel slats being attached to the upper layer at the heelward portionof the arched segment and the most heelward of the forepart slats beingattached to the upper layer at the toeward portion of the archedsegment.
 7. The midsole as defined in claim 6 further comprising: themost toeward of the heel slats and the most heelward of the forepartslats being thicker and having less flexible hinge regions than theother slats, the most toeward of the heel slats and the most heelward ofthe forepart slats comprising the arch support structure.
 8. The midsoleas defined in claim 6 wherein the support structure for the arch supportfurther comprises: at least one longitudinally and heightwise extendingsupport brace connected between the upper layer and the lower layer andbetween the most heelward slat of the forepart slats and the mosttoeward of the heel slats.
 9. The midsole as defined in claim 1 andhaving a centerline extending between a heel extremity and a toeextremity of the midsole and further comprising: the plurality of heelslats and the plurality of forepart slats extending at anon-perpendicular angle to the centerline with the medial ends of theslats being toeward of the their lateral ends.
 10. The midsole asdefined in claim 9 wherein the angle is between about ten and twentydegrees.
 11. The midsole as defined in claim 2 wherein the plurality ofheel slats are arranged in generally paralleling planes and theplurality of forepart slats are arranged in generally parallelingplanes.
 12. The midsole as defined in claim 1 wherein the upper andlower layers and longitudinally spaced plurality of heel slats andlongitudinally spaced plurality of forepart slats define a plurality ofhollow prism-shaped cells, each being defined by a pair of adjacentslats and a segment of each of the upper and lower layers.
 13. Themidsole as defined in claim 2 wherein the upper layer is sufficientlystiff to enable the upper layer to rock about the pivot region of thearch support structure in heelward and toeward directions.
 14. Themidsole as defined in claim 12 wherein the upper layer is sufficientlystiff to prevent distortion of the segments of the upper layer inresponse to rocking of the upper layer about the pivot region.
 15. Themidsole as defined in claim 1 wherein the arched segment and the archsupport structure define a generally triangular configuration with alower apex that defines a pivot region that functions as a fulcrum aboutwhich the upper layer and support structure can pivot.
 16. A footwearmidsole having a heel portion, a midportion and a forepart portion andcomprising: an upper layer; a lower layer spaced from the upper layer;each of the upper and the lower layer having a heel portion, amidportion and a forepart portion; the midportion of the upper layerbeing formed to define an arched segment; a bracing structure extendingbetween and connected to the upper and lower layers and supporting thearched segment, the lower end of the bracing structure being hingedlyattached to the lower layer at a fulcrum region to enable the bracingstructure and upper layer to pivot about the fulcrum region in heelwardand toeward directions; a plurality of generally planar heel slatsextending transversely between and hingedly connected to the heelportions of the upper and lower layers; a plurality of generally planarforepart slats extending transversely between and hingedly connected tothe forepart portions of the upper and lower layers.
 17. The footwearmidsole as defined in claim 16 further comprising: the heel slats beinginclined in an upward and heelward direction; and the forepart slatsbeing inclined in an upward and toeward direction.
 18. The footwearmidsole as defined in claim 17 further comprising: each pair of adjacentslats and segments of the upper and lower layers hingedly connected tothose slats defining a four-bar linkage.
 19. The footwear midsole asdefined in claim 18 wherein the four-bar linkages oscillate betweenexpanded and collapsed configurations as the upper layer pivots aboutthe fulcrum region.
 20. The footwear midsole as defined in claim 19wherein the four-bar linkages oscillate in opposite directions as theupper layer pivots.
 21. An article of footwear comprising: an upper; amidsole as defined in claim 1 attached to the upper; and an outsoleattached to the lower layer of the midsole.